The invention relates to a saw-tooth wire for producing a saw-tooth clothing for a roller or a carding element of a spinning room machine, such as a flat card, roller card, cleaner, opener or the like. The invention also includes a method and apparatus for producing the saw-tooth wire.
In general saw-tooth clothing has an elongate base region (foot) and an adjoining toothed region (blade) in which teeth are formed by cutting, the teeth comprising a tooth front, a tooth back and two side flanks, wherein between the tooth back and the tooth front of two successively arranged teeth there is a gullet.
Saw-tooth wire all-steel clothings are used, for example, in the processing of textile fibres to yarns, nonwovens or the like. Here, the individual saw-tooth wires of the saw-tooth wire all-steel clothings have, for example, a height of less than 2 mm and in the region of the tooth tips a width of 0.2 mm or less. To produce such saw-tooth wires, normally a wire-form starting material is first subjected to one or more drawing operations; between the individual drawing operations different heat treatment processes may also be carried out, in order at least partially to restore deformability to the already drawn wire. Following this preparation, the wire is normally provided with saw-teeth using a suitable mechanical stamping device (GB 2 257 164 A). In that process, the saw teeth produced by the stamping operation can also be hardened before or after the stamping operation. After the stamping operation small stamping residues are left behind on the surfaces of the saw-tooth wires.
Furthermore, on the surfaces of the saw-tooth wires there may be impurities caused by the preceding machining steps, such as, for example, scale, i.e. oxide residues, or dust residues which have occurred during the thermal treatment. These residues on the saw-tooth wires are troublesome during subsequent use of the saw-tooth wires for the processing of textile fibres, especially when used on high-performance machines, because individual fibres can be left clinging to the teeth of the clothing and the clothing consequently has an increased tendency to become clogged with fibres and impurities, such as bits of husk or the like. To avoid these disadvantages, saw-tooth wires intended for fabrication of saw-tooth wire all-steel clothings are normally also cleaned and polished after the stamping or hardening operation. In the case of the known saw-tooth wire, the tooth geometry is produced by stamping. One disadvantage is the high wear and tear on the tool. The tools have to be frequently reground or exchanged. Furthermore, production accuracy diminishes with wear, from the start to the end of a clothing, which can amount to several kilometers, and also from clothing to clothing. Another disadvantage is that different tools have to be made for different clothing types. Finally, the subsequent “flame” hardening of the teeth represents a further production step, which is also relatively inexact and hardly yields consistent results.
It is an aim of the invention to produce a saw-tooth clothing wire which avoids or mitigates the said disadvantages and in particular has teeth of relatively exact and uniform tooth geometry.